In addition estimate \((2.3.3.7)\) , p. 110 of [1]} for system (REF )
gives
\(\Vert u\Vert _{H^{2}} &\le &C\left( \Vert \mathrm {curl}\,f\Vert _{2}+\left\Vert \left( 2k-\gamma \right) \,h\cdot \mathrm {\tau }\right\Vert _{H^{2-\frac{1}{2}}(\Gamma )}\right) \\&\le &C\left( \Vert f\Vert _{H^{1}}+\left\Vert h\right\Vert _{H^{2}}\right). \) 
